In the field of optics, photonic crystals may be engineered to synthesize new optical materials with properties not found in natural optical materials. Due to the superprism effect of photonic crystals, they have been considered as candidates for compact, light demultiplexers. However, unfortunately, beams diverge when propagating inside photonic crystals, thus requiring significant propagation lengths and angular separation to be employed in demultiplexers or other devices requiring optical frequency separation or splitting, thereby rendering photonic crystals impractical for such uses.